Geoscience Reference
In-Depth Information
Table 24.2 Frequency
distribution of textural classes
of E part and Bt part of
lamellic (E & Bt) horizons
(Adapted from Official Soil
Series Descriptions of
118 pedons in lamellic
subgroups) (Bockheim and
Hartemink
2013
)
E part
a
Bt part
b
Number
%
S
LS
32
27.1
S
SL
8
6.8
S
SCL
2
1.7
S
S
1
0.8
LS
LS
7
5.9
LS
SL
18
15.3
LS
SCL
7
5.9
SL
SL
13
11.0
SL
SCL
8
6.8
SL
CL, C
3
2.5
L
L
1
0.8
L
SCL
1
0.8
L
C
1
0.8
SiL
SiL
6
5.1
SiCL
SiCL
1
0.8
No data
9
7.6
a
Analysis does not consider St, K, G Co and F modifiers
b
May have changed from CoSL to FSL or GSL to SL
Lamellic soils primarily have a mixed mineralogy (73 %), are in sandy or
sandy-skeletal textural classes (59 %), and have a cryic or frigid soil temperature
regime (59 %) and an udic or ustic soil-moisture regime (89 %; Fig.
24.3
).
24.4 Distribution of Soils with Lamellae
Soils in lamellic subgroups comprise a total area of 3.6 million ha in the USA
(Table
24.4
) and are found in 30 states (Fig.
24.4
). The primary regions
include glacial outwash and dunes of the Great Lakes region (43 % of the
total area of soils with lamellae), the Atlantic and Gulf coastal plains (23 %),
residual and colluvial surfaces from coarse-textured materials in the Rocky Moun-
tains (14 %), the sandy high plains of south central USA (11 %), and floodplain
deposits from Glacial Lake Missoula in northwestern USA (9 %). The map in
Fig.
24.4
is fairly comparable to that prepared 45 years ago by Dijkerman
et al. (
1967
) from consultations with NRCS soil scientists. The main differences
between our map and that of Dijkerman et al. are that we report more soils
with lamellae in CO and TX (Panhandle) and none in NE or western IA. Figure
24.4
suggests that soils with lamellae are less common in WI than previously reported
and now are mapped in LA and northwestern AL.
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